A typical waste and overflow system for a bathtub includes a standard overflow elbow that is held in sealed engagement with the back side of the tub in line with the tub overflow opening by self-tapping screws that extend through slots in a mounting bar overlying the overflow opening adjacent the front side of the tub and through the tub overflow opening into holes in a flange portion of the elbow.
When the waste and overflow system is initially installed, the elbow drain opening must be sealed in a fluid tight manner to permit pressure testing of the sanitary drainage system for leaks. Heretofore, this was typically done by inserting a gasketed test cap into the elbow drain opening through the tub overflow opening and threading a screw through a mounting hole in the mounting bar to cause the screw to press tightly against the test cap to hold the test cap in sealing engagement with the overflow elbow. After pressure testing is completed, the screw and test cap are removed and a cover plate is placed over the tub overflow opening and held in place by a mounting screw extending through the cover plate and into threaded engagement with the mounting hole in the mounting bar.
This particular system has the objection that it is time consuming to install both the drain elbow and test cap to insure a fluid tight seal during pressure testing of the system and then remove the test cap and replace it with a cover plate.